The neuromuscular basis of rhythmic struggling movements in embryos of Xenopus laevis

1982 ◽  
Vol 99 (1) ◽  
pp. 197-205 ◽  
Author(s):  
J. A. Kahn ◽  
A. Roberts
Keyword(s):  
Xenopus Laevis ◽  
Electrical Activity ◽  
Central Pattern Generator ◽  
Large Amplitude ◽  
Motor Nerve ◽  
Sensory Stimulation ◽  
Pattern Generator ◽  
Rhythmic Movements ◽  
Nerve Activity ◽  
Xenopus Embryos

Xenopus embryos struggle when restrained. Struggling involves rhythmic movements of large amplitude, in which waves of bending propagate from the tail to the head. Underlying this, electrical activity in myotomal muscles occurs in rhythmic bursts that alternate on either side of a segment. Bursts in ipsilateral segments occur in a caudo-rostral sequence. Curarized embryos can generate motor nerve activity in a struggling pattern in the absence of rhythmic sensory stimulation; the pattern is therefore produced by a central pattern generator.

Behavior-Dependent Activities of a Central Pattern Generator in Freely Behaving Lymnaea stagnalis

1997 ◽  
Vol 78 (6) ◽  
pp. 3415-3427 ◽  
Author(s):  
Rene F. Jansen ◽  
Anton W. Pieneman ◽  
Andries ter Maat
Keyword(s):  
Electrical Activity ◽  
Central Pattern Generator ◽  
Lymnaea Stagnalis ◽  
Central Pattern Generators ◽  
Pattern Generator ◽  
Egg Laying ◽  
Buccal Ganglion ◽  
Level Of Activity ◽  
Freely Behaving ◽  
Pattern Generators

Jansen, Rene F., Anton W. Pieneman, and Andries ter Maat. Behavior-dependent activities of a central pattern generator in freely behaving Lymnaea stagnalis. J. Neurophysiol. 78: 3415–3427, 1997. Cyclic or repeated movements are thought to be driven by networks of neurons (central pattern generators) that are dynamic in their connectivity. During two unrelated behaviors (feeding and egg laying), we investigated the behavioral output of the buccal pattern generator as well as the electrical activity of a pair of identified interneurons that have been shown to be involved in setting the level of activity of this pattern generator (PG). Analysis of the quantile plots of the parameters that describe the behavior (movements of the buccal mass) reveals that during egg laying, the behavioral output of the PG is different compared with that during feeding. Comparison of the average durations of the different parts of the buccal movements showed that during egg laying, the duration of one specific part of buccal movement is increased. Correlated with these changes in the behavioral output of the PG were changes in the firing rate of the cerebral giant neurons (CGC), a pair of interneurons that have been shown to modulate the activity of the PG by means of multiple synaptic contacts with neurons in the buccal ganglion. Interval- and autocorrelation histograms of the behavioral output and CGC spiking show that both the PG output and the spiking properties of the CGCs are different when comparing egg-laying animals with feeding animals. Analysis of the timing relations between the CGCs and the behavioral output of the PG showed that both during feeding and egg laying, the electrical activity of the CGCs is largely in phase with the PG output, although small changes occur. We discuss how these results lead to specific predictions about the kinds of changes that are likely to occur when the animal switches the PG from feeding to egg laying and how the hormones that cause egg laying are likely to be involved.

A Control System for a Flexible Spine Belly-Dancing Humanoid

2006 ◽  
Vol 12 (1) ◽  
pp. 63-88 ◽  
Author(s):  
Jimmy Or
Keyword(s):  
Central Pattern Generator ◽  
Humanoid Robot ◽  
Humanoid Robots ◽  
Pattern Generator ◽  
Degree Of Freedom ◽  
Rhythmic Movements ◽  
Walking Machines ◽  
Belly Dancing ◽  
Almost All ◽  
High Degree

Recently, there has been a lot of interest in building anthropomorphic robots. Research on humanoid robotics has focused on the control of manipulators and walking machines. The contributions of the torso towards ordinary movements (such as walking, dancing, attracting mates, and maintaining balance) have been neglected by almost all humanoid robotic researchers. We believe that the next generation of humanoid robots will incorporate a flexible spine in the torso. To meet the challenge of controlling this kind of high-degree-of-freedom robot, a new control architecture is necessary. Inspired by the rhythmic movements commonly exhibited in lamprey locomotion as well as belly dancing, we designed a controller for a simulated belly-dancing robot using the lamprey central pattern generator. Experimental results show that the proposed lamprey central pattern generator module could potentially generate plausible output patterns, which could be used for all the possible spine motions with minimized control parameters. For instance, in the case of planar spine motions, only three input parameters are required. Using our controller, the simulated robot is able to perform complex torso movements commonly seen in belly dancing as well. Our work suggests that the proposed controller can potentially be a suitable controller for a high-degree-of-freedom, flexible spine humanoid robot. Furthermore, it allows us to gain a better understanding of belly dancing by synthesis.

Phrenic nerve activity and occlusion pressure changes during CO2 rebreathing in cats

1976 ◽  
Vol 41 (4) ◽  
pp. 536-543 ◽  
Author(s):  
M. J. Evanich ◽  
M. Lopata ◽  
R. V. Lourenco
Keyword(s):  
Electrical Activity ◽  
Phrenic Nerve ◽  
Motor Nerve ◽  
Rate Of Change ◽  
Occlusion Pressure ◽  
Nerve Activity ◽  
Phrenic Nerve Activity ◽  
Co2 Rebreathing ◽  
Time Average ◽  
Breathing Room

Changes in phrenic nerve activity, quantified as a moving time average, PNG(t), were characterized during complete airway occlusion at functional residual capacity (FRC) and compared to simultaneously occurring changes in intratracheal pressure. In anesthetized cats breathing room air and during CO2 breathing, PNG(t) during occlusion was the same as that found during unobstructed breathing until it reached a value approximately corresponding to that at peak inspiration in the preceding unoccluded breath, the rate of change of PNG(t) usually remained the same but in a few cases (2 out of 11)increased. When intratracheal occlusion pressure was plotted as a function of PNG(t), both while breathing room air and during CO2 rebreathing, an approximately linear relationship was obtained. Thus, changes in intratracheasocclusion pressure obtained at FRC parallel changes in phrenic motor nerve activity. Quantification of electrical activity of respiratory nerves as a moving time average provides a means of characterizing changes in the average level of electrical activity during an inspiratory effort.

Cholinergic contribution to excitation in a spinal locomotor central pattern generator in Xenopus embryos

1995 ◽  
Vol 73 (3) ◽  
pp. 1013-1019 ◽  
Author(s):  
R. Perrins ◽  
A. Roberts
Keyword(s):  
Spinal Cord ◽  
Central Pattern Generator ◽  
Excitatory Amino Acid ◽  
Pattern Generator ◽  
Excitatory Input ◽  
Intracellular Recordings ◽  
Electrical Excitation ◽  
Spinal Interneurons ◽  
Xenopus Embryos ◽  
Spike Firing

1. We have investigated whether in Xenopus embryos, spinal interneurons of the central pattern generator (CPG) receive cholinergic or electrical excitatory input during swimming. The functions of cholinergic excitation during swimming were also investigated. 2. Intracellular recordings were made from rhythmically active presumed premotor interneurons in the dorsal third of the spinal cord. After locally blocking inhibitory potentials with 2 microM strychnine and 40 microM bicuculline, the reliability of spike firing and the amplitude of fast, on-cycle, excitatory postsynaptic potentials (EPSPs) underlying the single on-cycle spikes were measured during fictive swimming. 3. The nicotinic antagonists d-tubocurarine and dihydro-beta-erythroidine (DH beta E, both 10 microM) reversibly reduced the reliability of the spike firing during swimming and reduced the amplitude of the on-cycle EPSP by 16%. DH beta E also reduced the EPSP amplitude in spinalized embryos by 22%. These results indicate that interneurons receive rhythmic cholinergic excitation from a source within the spinal cord. 4. Combined applications of nicotinic and excitatory amino acid (EAA) antagonists or cadmium (Cd2+, 100-200 microM) resulted in complete block of the fast EPSP, suggesting that interneurons do not receive electrical excitation. 5. The nicotinic antagonists mecamylamine and d-tubocurarine (both 5 microM) reduced the duration of episodes of fictive swimming recorded from the ventral roots, in spinal embryos. When applied in the middle of a long episode, d-tubocurarine decreased the swimming frequency, ruling out an effect on the initiation pathway. The cholinesterase inhibitor eserine (10 microM) increased the duration of swimming episodes.(ABSTRACT TRUNCATED AT 250 WORDS)

Plateau potentials in motor neurons in the ventilatory system of the crab

1997 ◽  
Vol 200 (12) ◽  
pp. 1725-1736
Author(s):  
R Dicaprio
Keyword(s):  
Central Pattern Generator ◽  
Motor Neurons ◽  
Large Amplitude ◽  
Action Potentials ◽  
Experimental Tests ◽  
Pattern Generator ◽  
Plateau Potentials ◽  
Plateau Potential

The motor neurons in the crab ventilatory system have previously been considered to be passive output elements in that the generation of bursts of action potentials in these neurons during ventilation was thought to be due to cyclic inhibition and excitation from the interneurons in the ventilatory central pattern generator. This study demonstrates that the large-amplitude depolarization that underlies bursts of action potentials in ventilatory motor neurons is produced by a plateau potential. These motor neurons satisfy a number of the experimental tests that have been proposed for plateau potentials, such as triggering of the burst by a brief depolarization, termination of the burst by a hyperpolarizing input, and an all-or-none suppression of the depolarizing potential by the injection of hyperpolarizing current.

Responses of young Xenopus laevis tadpoles to light dimming: possible roles for the pineal eye

2000 ◽  
Vol 203 (12) ◽  
pp. 1857-1867 ◽  
Author(s):  
D. Jamieson ◽  
A. Roberts
Keyword(s):  
Xenopus Laevis ◽  
Water Column ◽  
Central Pattern Generator ◽  
Water Surface ◽  
Pattern Generator ◽  
Cement Gland ◽  
Solid Objects ◽  
Floating Objects ◽  
Behavioural Significance

When the light is dimmed, the pineal eye of hatchling Xenopus laevis tadpoles excites the central pattern generator for swimming, but the behavioural significance of pineal excitation is unclear. We show that tadpoles spend 99 % of their time hanging from the surface meniscus or solid objects using mucus secreted by a cement gland on the head. Attachment inhibits swimming, but unattached tadpoles swim spontaneously. Provided that their pineal eye is intact, they attach closer to the water surface in the dark than in the light and attach preferentially to the underside of floating objects that cast shadows. Dimming causes tadpoles swimming horizontally to turn upwards and is very effective in initiating upward swimming in unattached tadpoles. Similar pineal-dependent responses during swimming are present up to stage 44. Pinealectomy blocks responses to dimming at all stages. Recordings from immobilised tadpoles reveal that light dimming induces faster fictive swimming and that pineal activity is increased for up to 20 min during sustained light dimming. We suggest that the increase in pineal discharge during dimming increases the probability of upward swimming and, in this way, increases the probability of tadpoles attaching to objects higher in the water column that cast shadows.

Unique spectral peak in phrenic nerve activity characterizes gasps in decerebrate cats

1986 ◽  
Vol 60 (3) ◽  
pp. 782-790 ◽  
Author(s):  
C. A. Richardson
Keyword(s):  
Central Pattern Generator ◽  
Phrenic Nerve ◽  
Central Pattern Generators ◽  
Power Spectra ◽  
Pattern Generator ◽  
Respiratory Pattern ◽  
Nerve Activity ◽  
Phrenic Nerve Activity ◽  
Spectral Peaks ◽  
Decerebrate Cats

The respiratory pattern of gasping has been characterized on the phrenic nerve as rapidonset, rapid-rise, large-amplitude bursts of neural activity. Furthermore, medullary sites critical for the neurogenesis of gasping have been identified and are not the sites of identified respiratory neurons, such as the dorsal and ventral respiratory groups. I classified envelopes of phrenic nerve activity as eupneic breaths, or gasps based on the time-domain features of duration, shape, and amplitude. Gasps were elicited by hypoxia and low blood pressure in 9 of 12 decerebrate cats. Inspiratory times were 1.15 +/- 0.43 (SD) for eupneic breaths and 0.55 +/- 0.18s for gasps. The high-frequency peaks in the power spectra of phrenic nerve activity were at 80 +/- 13 Hz for eupneic breaths and at 120 +/- 21 Hz for gasps. Three of the 12 cats developed a breathing pattern that began as a normal breath and terminated in a gasp. Power spectra of the normal portion had eupneic spectral peaks (75 +/- 24 Hz); power spectra of the gasp portion had the high peaks at 110 +/- 23 Hz, a value 1.5 times higher than that for the normal peaks. Although this analysis of peripheral nerve activity cannot distinguish between two central pattern generators at two distinct anatomical sites or one pattern generator operating in two distinct modes, the fact that gasps were much shorter in duration and had markedly higher spectral peaks than control breaths supports the idea that the central pattern generator for gasping is not the central pattern generator for eupnea.

The neuromuscular basis of swimming movements in embryos of the amphibian Xenopus laevis

1982 ◽  
Vol 99 (1) ◽  
pp. 175-184
Author(s):  
J. A. Kahn ◽  
A. Roberts ◽  
S. M. Kashin
Keyword(s):  
Xenopus Laevis ◽  
Electrical Activity ◽  
High Speed ◽  
The Body ◽  
Muscle Physiology ◽  
Muscle Fibres ◽  
Xenopus Embryos ◽  
Conduction Pathway ◽  
High Speed Cinematography

When removed from their egg membranes, Xenopus embryos can swim. High-speed cinematography shows that, in swimming, lateral undulations pass rostro-caudally down the body. The swimming rhythm period is 40–100 ms. In swimming, electrical activity in myotomal muscles alternates on opposite sides of a segment and sweeps rostro-caudally in ipsilateral myotomes. Myotome muscle physiology was examined. Muscle fibres are electrically coupled to each other, and the fibres are able to spike. The possible role of a myotomal conduction pathway in swimming is discussed.

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